Hypermagnesemia in a 20-month-old healthy girl caused by the use of a laxative: a case report.

Background: Hypermagnesemia can be a fatal condition and should be diagnosed early on. Most reports of hypermagnesemia have been of adults with impaired renal function. We describe the case of a pediatric patient without renal dysfunction who developed severe hypermagnesemia.

Case Presentation: A healthy 20-month-old Asian girl presented to our emergency department with episodes of vomiting and a reduced level of consciousness. The neurological examination showed a symmetric decrease in muscle tone, and the deep tendon reflexes were decreased. On admission, her magnesium (Mg) level was 11.0 mg/dL after receiving magnesium oxide for 4 days because of constipation. She was immediately administered calcium gluconate infusion (3.9 mEq), and then was continuously infused with it (0.23 mEq/h) as a Mg antagonist to cardiac side effects. She was kept hydrated with 0.9% sodium chloride to maintain good urine output to excrete the Mg. The level of the serum Mg decreased to 2.4 mg/dL, enabling her to regain consciousness. During 5 years of follow-up, she was neurologically well, without the recurrence of hypermagnesemia.

Conclusions: Even in the absence of significant renal dysfunction, the prescription of a laxative containing Mg for constipation can result in severe hypermagnesemia. In addition, the symptoms of hypermagnesemia are nonspecific, and early diagnosis is difficult unless it is actively suspected.